Burglar alarm



June 20, 1967 L. A. BIRRE'NKOTT BURGLAR ALARM 2 Sheets-Sheet i Filed Feb. 12, 1965 LOUIS A. BIRRENKOTT IN V EN TOR.

AGENT June 20, 1967 L. A. BIRRENKOTT BURGLAR ALARM 2 SheetsSheet 2 Filed Feb. 12 1965 I" WU LOUIS A. BIRRENKOTT INVENTOR.

I BY I AGENT United States Patent 3,327,300 BURGLAR ALARM Louis A. Birrenltott, 965 Ellis Court, Eugene, Oreg. 97405 Filed Feb. 12, 1965, Ser. No. 432,172 4 Claims. (Cl. 340-283) This invention relates to alarm devices and more particularly to an audible signalling device adapted for attachment to or suspension from a doorknob and actuated by an off center overbalance when the door knob is turned in either direction.

A primary object of this invention is to provide an alarm device of this character which is of simple, inexpensive and compact construction, reliable and positive in operation and particularly well suited, through not restrictively, for use by travelers as Well as homeowners.

Another object is the provision of new and novel means which render the device self-adjusting to door knobs of various diameters and configurations.

A still further object is the provision of spring urged electrical contact means provided within the unit whereby the electrical contacts also provide means for locking the device in an overbalanced-actuated position which requires the device to be manually repositioned before the alarm circuit is opened.

A final object of this invention is the provision of an ON-OFF switch which operates in conjunction with a pair of apertured discs which provide a visual ON-OFF indication for the alarm circuit.

The foregoing and other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof and in which:

FIGURE 1 is a front elevational view of one embodi ment of the alarm device, suspended from a door knob and with fragments broken away for convenience of illustration.

FIGURE 2 is a side elevational View of FIGURE 1 with fragments similarly broken away.

FIGURE 3 is a sectional plan view taken approximately along line 3-3 of FIGURE 1.

FIGURE 4 is a bottom end view of FIGURE 1.

FIGURE 5 is a fragmentary sectional view taken along line 55 of FIGURE 1.

FIGURE 6 is a front elevational view of a modified form of the invention with fragments broken away.

FIGURE 7 is a side elevational view of FIGURE 6 with additional fragments removed, and

FIGURE 8 is a wiring diagram.

With further reference to the drawings and particularly FIGURE 1 thereof, reference numeral 1 indicates generally a cylindrical housing comprising upper and lower parts indicated respectively at 2 and 3 threadedly interconnected as at 4. Swingably attached by a pivot pin 6 within the upper part 2 and extending through an opening 2A therein is a flexible clamping member indicated generally at 5. The flexible clamping member 5 is of generally circular shape having a normal diameter slightly less than that of a standard sized door knob 7. To accommodate the door knob, the clamping member is sprung radially by means of finger-tip pressure upon a pair of clip members 8 which are spot welded to the clamping members as at 8A. (FIGURE 5). The clamping member 5 along with clips 8 are formed from spring steel and coated with a silicon rubber to provide a somewhat tacky gripping surface resulting in a positive attachment to the door knob.

An extension 9 of the clamping member is reduced in width at its bottom end, terminates within the upper part 2 of the housing 1 and thereat provided with an elecice trical contactor 10 insulated from the extension as at 11. The extension 9 is also flanged as at 12 to slidably receive the pin 6.

An elongated U-shaped frame 13 is suspended from the pin 6 by its legs 13A13B and held firmly in place by abutment of the legs with the interior top wall of the upper part 2 of the housing. A compression spring indicated at 14 is carried by the pin 6 and confined between vertical frame leg 13A and one of the flanges 12. Adjacent the opposite end of the pin 6 and secured in place thereby is a terminal block 15 of dielectric material provided with a pair of electrical contacts 15A and 15B inset respectively within recesses 15C and 15D. These contacts are in spaced relationship along an arc defined by the path of the electrical contactor 10 and extend through the terminal block 15 and int-o a recess formed in the back side thereof and thereat in circuit with a downwardly biased spring finger 16.

The contact door 10 terminates in a convex end portion of a length greater than the depth at which the contacts 15A and 15B are recessed to provide a camming surface on which the terminal block 15 Will ride when moved relative to extension 9 of the clamping member 5. Movement of the contactor 10 out of contact with either of contacts 15A or 1513 will be resisted :by the spring 14. Accordingly, once the contactor 10 has operatively moved onto one of the recessed contacts manual repositioning of the housing will be required to open the circuit.

A C-cell battery B is positioned within the U-shaped frame member 13 by inwardly struck ears 13C and is supported at its bottom end by, and in electrical circuit with, a buzzer 17 which is secured Within the frame by means of a pair of tabs 18 struck therefrom and provided with fastening screws 19.

A pair of apertured discs 20 and 21 of dielectric material are mounted at the lower end of the U-shaped frame by means of a post 22. The upper disc 21 is rotatable about the post and is provided with a metallic clip 23 which is adapted to be rotated into contact with a terminal 24 on the disc 20 to provide an ON-OFF switch. To secure the disc 20 against rotation, a projection 25 is provided on the interior of the lower part 3 of the housing to engage a corresponding recess 26 within the disc.

The disc 21 carries an arm 27 depending therefrom which extends through a limit stop in the form of an elongated opening 28 in the disc 20 to provide means for opening the alarm circuit to render harmless accidental misalignment of the clamping member 5 and the housing 1, as could occur during transit. If so desired, the ON-OFF switch may be dispensed with and instead the battery removed from the housing prior to transit.

The electrical circuit of both forms of the invention comprises the battery B, buzzer 17 grounded to the frame 13, clip 23 also grounded to the frame by a wire 29, terminal 24, a wire 30 connecting terminal 24 with the contactor 10, contacts 15A and 15B, and the spring finger 16.

In the modified form of the invention shown in FIG- URES 6 and 7, the alarm is secured to the door knob by means of a two-piece clamping member indicated generally at 5A which may be of a high-impact type plastic material. A coil spring 31 urges the clamping member 5A centripetally about a hinge pin 32 to compress against a door knob 7 a strip of foam rubber 33 provided within a groove 34 formed on the interior of the clamping member. As shown in broken lines in FIGURE 6, the clamping member 5 is opened for placement upon the door knob by pressure applied to finger grips 35 and 36.

This modified form of the invention provides electrical contact means which serves additionally to lock the housing 1a in an overbalanced alarm position which requires manual re-positioning of the housing 1a in two different directions to open the alarm circuit. A contact door 10a in the form of a cylindrical pin terminating in a flat end wall is provided at the clamping bottom end of the extension 9a for axial insertion within either of a pair of recesses 37 or 38 in the terminal block 15E and held therein by a spring member MA. A pin 6A connects extension 9A to the housing. Contacts 15F and 15G are centrally disposed within the recesses 37 and 38 respectively which are defined by a circumferential wall which corresponds to and confines the contactor 10A against lateral movement.

The operation of both forms of the alarm device is similar and hence will be described as related to the first form wherein the device is secured to the door knob in the manner described with the cylindrical housing 1 vertically depending from the door knob 7. Prior to attachment disc 21 is rotated to close contacts 2324 and when so moved will result in the apertures of both discs being in juxtaposition to provide a visual ON indication, Rotation of the outside door knob by an intruder causes the housing 1 to be swung upwardly in either direction until the housing overbalances and gravitates to either the broken line or dashed line position of FIGURE 1 cansing contact 15A or 15B to be moved toward contact 10.

The convex end of the contactor 10, as shown in the first form of the invention, is seated against contact 15A or 15B by spring member 14 acting upon the housing 1 to move it to the left, as shown in broken lines in FIGURE 2. It is understood that minor variations in the rate of spring member 14, the relationship of contacts 15A and 15B, and the weight of the housing may be made to achieve the sensitivity desired.

Normal realignment of the housing and clamping member will cause the housing to re-position itself to the right,

.as viewed in FIGURE 2, as the terminal block 15 rides over the convex end portion of the contactor 10.

In the modified form of the present invention as viewed in FIGURES 6 and 7 it will be seen that upon overbalancing of the housing 1A the fiat end of contactor 10A will engage either of the contacts 15F15G. Spring member 14A will retain the contactor and contact in locked engagement regardless of subsequent rotation of the door knob by the intruder. To reset the housing 1A to a neutral (open circuit) position relative to the extension 9A it is necessary that first the housing be moved horizontally along pin 6A to disengage the contactor from one of the recesses 37 or 38 and secondly swung about said pin.

While I have shown two forms of the invention, I am aware that many minor changes therein will readily suggest themselves to others skilled in the art without departing from the spirit and scope of the invention. Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

1. An alarm device associated with a door knob, and comprising;

an elongated housing including a battery and electric warning device,

an expansible clamping member attaching said housing to the door knob and terminating in a depending extension into the housing,

pivot means swingably and slidably attaching the upper end of said housing to said depending extension,

a single electrical contactor carried by said extension and swingable in an arcuate path upon rotation of the door knob,

a pair of electrical contacts mounted in recesses formed 'within said housing and movable alternately thereby upon overbalancing of the housing into circuit closing contact with said single electrical contact, and

spring means disposed between said housing and said extension urging said housing and specifically said contact carried thereby horizontally into engagement with said contactor subsequent to overbalancing of said housing.

2. An alarm device as claimed in claim 1 wherein said contactor is of cylindrical shape terminating in a rounded end portion for engagement with said contacts within said recesses,

said end portions constituting a camming surface whereby said housing is horizontally displaced upon relative movement between said contactor and said recesses;

3. An alarm device as claimed in claim 1 wherein said contactor is of cylindrical shape and terminates in an end portion having a fiat end wall for engagement with said contacts within said recesses.

4. An alarm device as claimed in claim 1 wherein said clamping member comprises a continuous band of flexible material for gripping the door knob.

References Cited UNITED STATES PATENTS 740,684 10/ 1903 Needham 24256 775,723 11/1904 Getto 340-274 1,110,893 9/1914 Caulkins 340-276 1,491,286 4/1924 Calhoun 24255.1 2,423,610 7/1947 Miller 340--274 NEIL C. READ, Primary Examiner.

D. L. TRAFTON, Assistant Examiner. 

1. AN ALARM DEVICE ASSOCIATED WITH A DOOR KNOB, AND COMPRISING; AN ELONGATED HOUSING INCLUDING A BATTERY AND ELECTRIC WARNING DEVICE, AN EXPANSIBLE CLAMPING MEMBER ATTACHING SAID HOUSING TO THE DOOR KNOB AND TERMINATING IN A DEPENDING EXTENSION INTO THE HOUSING, PIVOT MEANS SWINGABLY AND SLIDABLY ATTACHING THE UPPER END OF SAID HOUSING TO SAID DEPENDING EXTENSION, A SINGLE ELECTRICAL CONTACTOR CARRIED BY SAID EXTENSION AND SWINGABLE IN AN ARCUATE PATH UPON ROTATION OF THE DOOR KNOB, A PAIR OF ELECTRICAL CONTACTS MOUNTED IN RECESSES FORMED WITHIN SAID HOUSING AND MOVABLE ALTERNATELY THEREBY UPON OVERBALANCING OF THE HOUSING INTO CIRCUIT CLOSING CONTACT WITH SAID SINGLE ELECTRICAL CONTACT, AND SPRING MEANS DISPOSED BETWEEN SAID HOUSING AND SAID EXTENSION URGING SAID HOUSING AND SPECIFICALLY SAID CONTACT CARRIED THEREBY HORIZONTALLY INTO ENGAGEMENT WITH SAID CONTACTOR SUBSEQUENT TO OVERBALANCING OF SAID HOUSING. 